Traditionally, adherent creams and powders used to secure dentures within the mouth were prepared from such materials as finely powdered natural gums, i.e. karaya, acacia or tragacanth gum. These materials have the particular property of swelling to many times their original volume upon the addition of water to form a gelatinous or mucilaginous mass. Denture adhesive powders may be a combination of one or more natural gums, generally flavored with pleasant tasting volatile oils. Many other additives may also be included such as antiseptics, stabilizers, bactericides, special deodorants, plasticizing agents, fillers, coloring agents, and the like.
Cream forms of denture adherents, prepared from finely ground particles of the natural gums dispersed in a cream base, are also available and may be used instead of powder compositions. In any event, when wet with water, the natural gum in either the cream or powder formulation expands to become a viscous gel which acts as a cushion and an adherent between the denture plate and the gum tissue.
Denture adhesive cream formulations have also been comprised mainly of natural or synthetic polymer materials suspended in an anhydrous oleaginous vehicle system comprising mineral oil and petrolatum. The petrolatum is added to thicken the formulation consistency to that of a cream which is extrudable from tubes. These formulations necessarily must be thick to prevent syneresis or phase separation because the solid adhesive particles are merely suspended in the oily vehicle. This thickness of the formulation makes them somewhat difficult to squeeze out from the tube.
Additionally, although these formulations are fairly thick in consistency at ambient room temperature of about 25.degree. C., they are not thermally very stable and hence tend to thin out evenly at slightly elevated temperatures. For example, at the body/mouth temperature of 37.degree. C. at which these formulations are used, they tend to thin out and become runny and therefore ooze out from under the denture during use. The phenomenon is naturally further aggravated when hot liquids and foods are consumed by denture wearers who use such denture adhesive products. This problem with oozing of denture adhesive from under the denture into the mouth is considered to be one of the major drawbacks to the consumer due to the unpleasant taste and mouth feel. Additionally, the holding property of the formulation that secures the prosthesis to the jaw is reduced due to the oozing or loss of product from under the denture.
One extremely desirable attribute of a good denture adhesive is that it develops a high degree of tack upon contact with saliva in order that the dentures be held in place as soon as they are seated in the mouth. It is also highly desirable that the mucilage is spread over the denture-mucosa interface in order to effectively seal the denture in place and that the mucilage possesses sufficient cohesive strength to withstand the stresses of mastication which act to rupture the seal and thus dislodge the denture. The denture fixation must also exhibit sufficient resistance to degradation under the extreme environmental temperature changes which occur in the oral cavity during such common actions as drinking coffee or other hot beverages and foods.
The dental adhesive compositions of the present invention afford the excellent adhesion of the dentures to the oral tissues of the gums and jaw regions of the mouth while at the same time are non-toxic so as to not adversely affect these same oral tissues. The adhesive cream provides excellent cohesive properties with a high degree of tack to prevent denture sliding. The composition possesses a soft, creamy texture with no unpleasant taste or mouthfeel.
Historically, a denture adhesive cream is made by preparing a base and mixing the base with other components which will provide sufficient adhesion with adequate cohesive strength to hold the dentures in place. This adhesive cream must be non-toxic and non-irritating to oral tissues since they are in direct contact with the tissues and the dental prostheses. For a denture adhesive to be practical and provide comfort, it must not have an unpleasant odor and must have a pleasant taste and aroma. It also must exhibit adequate stability, and quickly hydrate when in contact with the oral mucosa. It must also provide sufficient tack to form a strong cohesive strength and must be durable. In addition to all of the above, product appearance and the ease of application of the product are also significant factors.
The dental adhesive composition must not only hydrate when contacted with oral fluids in order to form both a cushion and a cohesive seal with the oral tissues of the maxillary arch or inner surface of the mandible, but it must also at the same time not be soluble when exposed to these same fluids such as saliva and the various foods and beverages that are exogenously introduced into the mouth.
Denture adhesive creams and powders are well known in the art and many commercially available products have been around for quite some time. The materials comprising these denture adhesives have varied but generally have remained somewhat constant in order to provide the necessary functional attributes. Oils, fatty acids esters, petrolatum and combinations of these have always been used as the primary components to produce the adhesive cream base. The use of hydrophilic colloids, active ingredients, flavors, dyes, sweeteners, therapeutic agents and preservatives in the vehicle in order to prepare a uniform paste have also been practiced in the development of a denture adhesive cream. All these require the presence of a hydrocarbon mineral oil to act as a solvent and thickener for the adhesive cream base.
U.S. Pat. No. 4,318,742 to Lokken discloses and claims a denture adhesive comprised of a major amount of gum base consisting of natural and synthetic gums, isobutylene/isoprene rubber, petrolatum waxes, polyethylene and mixtures thereof. The gum base is combined with a hydrophilic polymer such as methacrylic acid esters and carboxymethyl cellulose and the like to form the adhesive which may include other excipients such as plasticizers, tackifiers, sweeteners, flavors and the like to modify the adhesives sensory and theological characteristics.
U.S. Pat. No. 4,521,551 to Chang et al. teaches and claims various denture fixative compositions comprising a water soluble partially neutralized alkyl vinyl ether maleic acid/anhydride copolymer and at least one hydrophilic polymer such as sodium carboxymethyl cellulose polyethylene oxide or hydroxypropyl guar. When contacted with salvia said composition develops a high degree of tack and viscous mucilage which readily spreads over the denture-mucosal interface so as to fill the gaps between the dentures and gum and provides a suction-type seal.
U.S. Pat. No. 5,006,571 to Kumar et al. describes a denture adhesive composition consisting of petrolatum, natural and synthetic oils, waxes, vegetable oil waxes and the like. The useful oils mentioned include mineral oil, vegetable oils such as corn, soy bean, cottonseed, castor, palm and coconut oils and animal oil such as fish oil and oleic acid. In general, the oils are incorporated in amounts of about 1.0% to about 30.0% by weight of the total denture adhesive composition with amounts of from about 10% to about 25% being preferred. An optional component in the formulation of the invention is the use of fumed silica in the amount of about 0.5% to 6.0%..
U.S. Pat. No. 5,093,387 to Schobel et al. discloses a denture adhesive base composition with an anhydrous mixture of cationic derivatives of guar gum, a mixed sodium/calcium salt of methyl vinyl ether maleic anhydride and sodium carboxymethyl cellulose. Fumed silica is disclosed as an optional additive in the formulation of the adhesive. The cream base material also includes a selected group of natural and synthetic oils and mixtures thereof. At least one cream base material is selected from the group of petrolatum, synthetic oils and mixtures thereof. There is no teaching of a natural oil or vegetable oil with fumed silica as total replacement of the hydrocarbons in the vehicle.
None of the prior art has successfully formulated a dental cream adhesive base that is free of hydrocarbon mineral oils which impact a far lesser degree of objectionable odor and taste. The novel adhesive base composition of the present invention is thickened with fumed silica which imparts a low viscosity to the cream, a far better spreadability yet still maintains a high level of cohesion.